So squirrels are fairly common in Vermont. This is because the population of squirrels is so high. If you sit down and be quiet you can see a ton of them.

A moose on the other hand have a much much smaller population. So you could do the same activity, sitting in down in the woods and being quiet, and you probably won't see one. This is due to the smaller population.

In this cheesey grade school story, the squirrels are white people. The moose are PoC.

So when talk about population and probability, you're more likely (probable) to see something that there is more of (population).

Hope that helps.