Short story where a man ends up in the future when humanity has evolved into something unrecognisable to him & with no way back commits suicide rather than be alone.
I think his 'time travel' is a result of time dilation during a long space journey, cryosleep of some sort is a possibility but I'm pretty sure the main cause was time dilation, but either way it's a one way trip & there's no way 'back' to his own time.
Humanity has changed so much they appear grotesque & monstrous to him.
He ends up as a zoo (or museum?) exhibit or curiosity.
There's no way back to his time & he's the last 'human' he'd recognize as such so he commits suicide (jumps from somewhere high as I remember) rather than live the rest of his life alone.
The story would have been from the 70's or very early 80's, perhaps older.