Does it say in the Old Testament somewhere “not to intermix ourselves but to remain with our own likeness?”

Answer:

There were verses in the Old Testament like this but it was basically because the other races did not serve God but pagan idols.

In the New Testament we have a similar command:

2 Corinthians 6:14  Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?

God doesn’t see the color of our skin but He does see the condition of our heart and soul.

Good question,
Pastor Brad