That's the point he's strong. Ashura never was strong when he was coming up. Hashirama never struggle, therefore he became someone else. Hashirama was naturally strong. He was born with a Kekkei Genkai known as Mokuton. Only Shinobi in history to be born legitimately with Mokuton. He train a lot, was very strategic, intellectual, great in all forms of taijutsu, kenjutsu, senjutsu, ninjutsu, kenjutsu and the list goes on. Hashirama was a warrior since he was small. Battles between Senju's and Uchiha's ravage through his whole life. He had to become strong to overcome the battles. This is why he wasn't like Ashura therefore he didn't fully awaken Ashura like Naruto did. Do you get where I am coming from?