If he only said "I cleaned my shoes", they could be dirty again. Now you know the difference between present perfect and simple past. English grammar, it's weird (but every language's is, to be fair).
Don't even get me started on whoever decided that through, trough, and though, don't rhyme, but pony and Bologna do. I bet he was a colonel who kept a journal.... Asshole...
To be pedantic that's not grammar but orthography (which in English is even weirder). English is just a mutant amalgamation of Germanic, Romance and Celtic languages and man, it shows.
You're clearly a bit of a fellow word nerd. Do you have any feelings about the fact that none of that matters anymore if we all just agree that it doesn't, which one could have an easy time arguing that we have? Sometimes, after spending a rousing five minutes explaining the MOST correct pluralization of 'octopus', the only answer I can give to the inevitable question of "why does it matter?" Is "it doesn't".