I am someone who makes a lot of typos. (Sorry, editors.) There are a lot of reasons for this. My fingers are dumb, I don't know how to spell, and I am not very good at proofreading. Hell, one time I didn't get a job because I put down the wrong phone number on my application.
There is the temptation to say I should just give up on being a writer because I make too many mistakes for it to ever happen, but here's the thing. Sometimes little mistakes can lead to great discoveries. Penicillin was discovered because a scientist didn't bother to clean his tools. And, yes, I do think that accidentally typing "teh" is just as important as discovering penicillin.
Back me up here, other writers.