Here's my dissertation why Usopp has always been firetmate whether in the original plot and in current times. Let's start off with the facts.
When Oda first drafted the story Usopp was firstmate. There's no disputing that but one of his editors talked him out of it(the bastard). Usopp was the only character in the original designs to wear a hat other than Luffy. Getting to the plot we all know and love luffy invited Usopp on the crew and usopp jokingly said as captain right? Next we'll jump into the scene that matters most. Luffy and Usopp discuss their roles. Usopp says he'll LET luffy be captain but if he ever fails his duties as captain he'll step in and take over. LUFFY AGREES.
Now lets talk about the duties of a vice captain. One is to take over if the captain is out or unable to lead. We will come back to that later. Another important aspect is to be a leader and aspire/mentor the rest of the crew. In Usopp's very first arc Luffy and Zoro are moved by Usopp's courage and feel the motivation to help him. His very bravery to do something he feared doing cemented all three pirates to aid Usopp. Nami included who at that point was very self centered and planned on leaving the crew anyway.
If we talk about mentoring Usopp has done alot of that as he's seen as an older brother figure to Luffy Nami and chopper. Not to mention making Naminmuchbstronger by giving her a weapon. Usopp fearlessly attacking arlong to save namis makeshift father cemented and established their dominance as liberators. Up until this point Zoro has been fighting and doing nothing more.
So let's do a quick round up to Usopp's importance to the crew. Deal with luffy, first to appear on a bounty picture next to Luffy, ties with shanks crew same as luffy. Becomes a symbol of liberation including having statues built of him same as Luffy. Having the same exact bounties as Luffy. I could go on and on but this is enough.
Let's focus on the deal Usopp made with Luffy. Luffy is the captain but if he fails in his duties Usopp will take over. The very definition of a firstmate. In Luffy's fight against Rob Lucchi Luffy is so beaten up and tired from g2 usage and other damage that he lays defeated in front of his enemy. In that moment Usopp steps in and threatens to squash Rob Lucchi like a kitten if Luffy doesn't get up and fight. Probably the most important battle in the story thus far and Luffy has fallen a bit short. Usopp then gives his captain the best speech in OP history giving his captain strength to stand up and win the war.. deal fulfilled. In the same arc Zoro fought a giraffe.
Now let's end with the very importance of Usopp in the crew. Got the crew their first proper ship, created the flag destroyed the wg flag, we have deleted scenes where Garp tells usopp to protect Luffy.
For reasons I won't get into Usopp being the fristmate was scrapped and usopp instead nice big juicy racist lips. I'll let you speculate why they made that change. One Piece may not have had 10 years of sucking had Oda not change his mind on keeping Usopp firstmate.
When Oda first drafted the story Usopp was firstmate. There's no disputing that but one of his editors talked him out of it(the bastard). Usopp was the only character in the original designs to wear a hat other than Luffy. Getting to the plot we all know and love luffy invited Usopp on the crew and usopp jokingly said as captain right? Next we'll jump into the scene that matters most. Luffy and Usopp discuss their roles. Usopp says he'll LET luffy be captain but if he ever fails his duties as captain he'll step in and take over. LUFFY AGREES.
Now lets talk about the duties of a vice captain. One is to take over if the captain is out or unable to lead. We will come back to that later. Another important aspect is to be a leader and aspire/mentor the rest of the crew. In Usopp's very first arc Luffy and Zoro are moved by Usopp's courage and feel the motivation to help him. His very bravery to do something he feared doing cemented all three pirates to aid Usopp. Nami included who at that point was very self centered and planned on leaving the crew anyway.
If we talk about mentoring Usopp has done alot of that as he's seen as an older brother figure to Luffy Nami and chopper. Not to mention making Naminmuchbstronger by giving her a weapon. Usopp fearlessly attacking arlong to save namis makeshift father cemented and established their dominance as liberators. Up until this point Zoro has been fighting and doing nothing more.
So let's do a quick round up to Usopp's importance to the crew. Deal with luffy, first to appear on a bounty picture next to Luffy, ties with shanks crew same as luffy. Becomes a symbol of liberation including having statues built of him same as Luffy. Having the same exact bounties as Luffy. I could go on and on but this is enough.
Let's focus on the deal Usopp made with Luffy. Luffy is the captain but if he fails in his duties Usopp will take over. The very definition of a firstmate. In Luffy's fight against Rob Lucchi Luffy is so beaten up and tired from g2 usage and other damage that he lays defeated in front of his enemy. In that moment Usopp steps in and threatens to squash Rob Lucchi like a kitten if Luffy doesn't get up and fight. Probably the most important battle in the story thus far and Luffy has fallen a bit short. Usopp then gives his captain the best speech in OP history giving his captain strength to stand up and win the war.. deal fulfilled. In the same arc Zoro fought a giraffe.
Now let's end with the very importance of Usopp in the crew. Got the crew their first proper ship, created the flag destroyed the wg flag, we have deleted scenes where Garp tells usopp to protect Luffy.
For reasons I won't get into Usopp being the fristmate was scrapped and usopp instead nice big juicy racist lips. I'll let you speculate why they made that change. One Piece may not have had 10 years of sucking had Oda not change his mind on keeping Usopp firstmate.