I did some lessons as a child and reached grade 4 (35 years ago!) . I didn't enjoy it much and did the minimum of practise. Haven't played at all since.
I don't think I have any natural ability, don't have a musical ear, couldn't name or play a note from hearing it and can't sing for toffee, but I have recently acquired a teach yourself book and have gone back to basics and am enjoying it.
It's the one DS2, who's just started lessons at 12yo was given by his teacher. Alfred's Basic Adult Piano Course Lesson Book Level 1. It has a very old fashioned looking cover but we both seem to be enjoying it and following it OK.
We have just rented a piano as DH wants to learn how to play. He is musical and is practising regularly. He is serious about it - in so far as he sees it as a way of relaxing.
I, on the other hand, have always thought of myself as non-musical (your description above fits me perfectly) but I have also been trying to play it a bit. I am not sure how seriously I will take this. But I am doing it because I enjoy it, and because I want to break that negative view of myself as not musical. I will never be an opera singer or perform on stage, but that doesn`t mean I can`t find it relaxing. I feel my brain working in new ways when I am concentrating on the piano. That must be good for my brain.
So, I would agree with Ferguson, do it for yourself and your enjoyment!
If you want to take it up seriously then I strongly recommend getting a tutor even if it's for once a month lessons. Probably not what you want to hear but you will progress much quicker learning from a living, breathing expert rather than trying to decipher instructions from a book.
It is never to late to learn an instrument. If you enjoy it, then go for it.
I recommend reading Matthew Syed's book "Bounce" (iirc) and similar stuff on the myth of inborn talent. Musicianship is very much a set of skills you can learn and talent has far less to do with it than putting the hours in! Definitely go for it and good luck (late starter cellist here)