In theory, maybe. But the vast majority of NFL coaches played in college, even if not at a high level. Even coaches you don't usually think of as players -- Belichick, McDaniels, Rex Ryan, etc . -- did play on their college football teams. It's a basic sign of taking the sport seriously.
What's more, the higher the level you reach as a player, the greater the chances of becoming an NFL coach, thanks to the experience, exposure and connections gained. The % of coaches who are former NFL players generally runs 20-25%, so wildly far above chance as to be unarguable as a factor.
FWIW, here are the percentages of African-American players at three levels of football.
22% high school
46% major conference college
70% NFL
If you take a weighted average to reflect the higher chances of NFL coaching careers for players at higher levels, you end up with an expected outcome of about 50% African-American coaches. Note this is not a "target" number. It's just what you would expect to naturally happen, all else being equal. The fact that the actual percentage never comes anywhere close to that suggests all else is not equal.