Can not commit before 1947 using git commit to past

Using git commit --date=‘YYYY-MM-DD HH:MM:SS’ -m “message”
we can only commit up to 1947 but not before that.

GitHub was founded in 2008. But it allows users to commit before that.

That sounds like something that’s related to Git itself, not GitHub. Best bring it up on the Git mailing list, as described here: Git - Community

I’m curious about your use case, I’ve seen a similar question before, in that case someone was trying to track changes in laws using Git, with author dates reflecting when the changes were actually made.