> Chinese characters are known to have persisted unchanged for thousands of years.

Are you kidding? Two thousand years ago they would have looked like seal script.

That radical is known today as the 宝盖 ("cover of 宝"), so here's the character 宝 itself. The roof is prominently featured: https://img.zdic.net/zy/jinwen/32_F420.svg

( You can see other instances from the same period at http://zdic.net/zd/zx/jw/%E5%AE%9D )

Would you be able to recognize the radical? Would you be able to recognize the character?