The Legend of Aikala: the Rise of the Reincarnated Dragon Clan

From being a math teacher who was unjustly shot to death, to being reincarnated as a dragon warrior, who knows what I've been through! In my previous life, I just wanted to be a good person, but my carelessness led to a miserable ending. The Great God said that these are not important, because in the next life I will not only take on the responsibility of saving the world, but also protect them? It's so difficult! In order to avoid making the same mistakes again, I decided not to be a human anymore, I wanted to transform into a dragon! (No system, a different world of swords and magic, slower pace, non-brainless and exciting plot, grand world view, more objective protagonist's growth path, all characters' IQs are online, happy ending HE)