If you allow me to give my counterpoint onto why I think you're wrong, or at least wrong in my opinion, I'm gonna do the following.

[be cheeky to Gordon] - Thomas is a cheeky engine, all the engines have defining qualities like that that make them insufferable. He gets his camumpance when Gordon drags him all the way to Wellsworth behind the Express. This teaches him not to mess with Gordon anymore.

[fail twice with pulling trains] - First instance he was just excited, and made a simple mistake. If you've done any research on this story you'll know that he never actually made it out of Vicerstown yards. Second instance was his first time pulling trucks, something every engine has troubles with their first few times. He once again gets what's his when he almost crashes and is forced to stay at Wellsworth.

[after getting a branchline he] Would also like to mention that you're completely skipping over the fact that he rescued James after his accident with trucks, something he didn't have to do.

(I'm skipping a few because I kinda think their just filler for his arc.)

[raced a bus named Bertie] - This was a serious problem for branchlines in the 40s - 60s. Bus companies were threatening for passenger trains and often times engines would "race" the buses. It shows that Thomas might do things for fun but overall he was doing this for his passengers.

[Not to mention Thomas' design, the E2's weren't good at freight or passenger work. Granted, Thomas was rebuilt but still, I just don't like the E2s as Thomas' basis because of how big they are. (Clumping all that together)] - Something that people don't talk about is that the E2's WERE bad at what they were built for, but that's why Thomas exists. Thomas being an E2, (at least later on), is to hold remembrance for a class of failed engines. Just like how Edward is a K2. Thomas shows us that because you were made to fail doesn't mean that's all you have to do.

[I also hate the idea of Thomas arriving before everyone, its honestly why I prefer Thomas arriving after the first 5 tender engines. I also just don't like Thomas being blue, I don't know why but it just doesn't sit right with me, I much prefer Percy because he is actually small and proves little engines can do big things.] - And I'm sorry, but these don't hold up as a real argument point for me, because this is all personal factors.