You must pick a point in human history before the 1950s to be spend the rest of your life in. What era and place would you choose?
You would still have the same age, gender, personality, skin color, etc. and you would be able to speak at least one local language and would know basic information of the era and place. Your family, social standing, and such would be randomly picked.
If I could speak the local language and know basic information about the era and place, I would join the Navajo people from whence 12.5% of my DNA originated because I identify with that the most, it's strong in me. I feel like a fish out of water currently. I would be so happy with them. In fact I was recently in Arizona and I wanted so much to join the Navajos but I know it doesn't work that way. You have to be born in there in order to assimilate.
And I'd choose a point in history long before they were conquered by Europeans. I don't want to deal with any of that traumatic massacre bullshit.
I reckon if you could get there 10 years early you could probably prevent the entire thing. If you were capable of convincing some of the larger groups within the americas of the impending invasion, there were certainly people and resources enough to put together a small navy and start patrolling the eastern coast. Throw is some modern knowledge of firearms and metallurgy to help them develop some cannon, and Columbus never makes it to America.
Back in Europe people assume him lost at sea, and leave the atlantic untouched for another generation. With that much time to prepare, who knows how things play out.