I just want to say that is kinda like Re:Zero, except no harem antics, the MC has even LESS skill than Subaru, but is 10,000 times better in wanting to improve. Instead of Re:Zero, it might be closer to 'All you Need is Kill', or 'Edge of Tomorrow', but again, the MC is even LESS talented, so it takes longer for him to improve. (in a subjective sense of course, objectively he still masters each thing in 'one day' )
Honestly, if someone distilled the very essence of shounen 'never giving up' and 'continuing forward through adversity with pure stubbornness', you'd get something like this.
While the MC can be frustrating because it 'takes so long' for him to learn something, he makes up for it by not being a wuss, lame, annoying, etc. Honestly the ONLY thing i dislike about him is his slow learning speed. Every other important feature that makes a person/character is great.
Also, side note: I love his squad. They're all batsht insane in their own way (it's a squad of misfits), but they all clearly like him for their own reasons, despite him being weaker than them in every way. There's MAD amounts of respect flowing around, and him being the one to rein them in is actually hilarious, especially because he is by all accounts a quiet and subdued person - he's just super f**ing intense on the inside. He just looks like he's got a poker face (and a social and developmental disorder) on the outside lol.