As in my other thread I am trying to get a better feel on what a +1 per level to basically all rolls boils down with regards to the internal logic of the game world. Again I should mention that obviously pathfinder isn't life simulator and edge cases will always give weird results, but I still think its interesting to think about those things.
So I was thinking a 20th level guy with all abilities at 10 has basically the same stats with a 1st level guy with all his abilities at 48, that is str 48 dex 48 con 48 int 48 wis 48 cha 48! So they have the same ac, attack bonus, saves, skill modifiers and resonance. Their only difference is in hp, damage and proficiency ranks increases.
However if the 20th level character gains skill increases for level they are basically the same in that aspect. (Also if the 20th level one has +5 longsword they will be very close damage wise)
Note that his stats are compared to a 20th level pc that has his abilities at 10. If his array is sth like 22 20 20 18 16 10, then the 1st level equivalent will be 60 58 58 56 54 48.
I think that this on some level at least demonstrates how much heavier and dense the new level bonuses are and what they actually represent.
I didn't mention the obvious that the levels dont add to ability checks. At least I haven't seen it mentioned anywhere that they do.