But it plays out with Black Americans and Indigenous Americans in higher rates. So your 3 points/explanations can be correct, but so can mine.

There is an overall higher worse throughline = racism is the highest/worst throughline, it stands out higher than your three. Because if it happens to one White guy for every 3 Black guys, consistently over years and a dozen+ decades, it is "racism" or colorism.

It is not the same percentage for Whites, they get stopped less, arrested less, convicted less, sentence not as long, on death row less, executed less,…. again percentage wise.

Here are some references I found very easily, and I have listened to the book at the bottom. You may want to look at the book as well, it shows how everything got started with police and statistics in the US back in the 1890s.

Current

https://www.usatoday.com/story/news/nation/2021/02/11/chicago-police-study-white-cops-more-likely-arrest-use-force/4439259001/

Fairly current

https://slate.com/news-and-politics/2015/08/racial-disparities-in-the-criminal-justice-system-eight-charts-illustrating-how-its-stacked-against-blacks.html

Historical

https://www.audible.com/pd/The-Condemnation-of-Blackness-Audiobook/B073ZLFCW6