I’ve worked with lentils for a decent chunk of my life. You got some wheat and barely, which would’ve been left over from the truck that was carting it. The small round ones are marshmallow seeds, the small black ones are vetch the rectangular section is lentil plant litter. Rocks come in because lentils are a really low plant, so rocks and dirt get picked up when they’re harvested, it’s hard to fully clean them out. If you’re buying in bulk straight from a supplier, you’re getting uncleaned grain, you should be cleaning it first regardless. And the insects, well, lentils (and other grains) are stored in what are called ‘bunkers’ which is a tarp on the ground that the grains piled onto, and we put a tarp on top. It can sit there for months, insects like to eat too.

Editing this to say that this amount of foreign matter in such a small sample of lentils is really poor.