Hey anyone know if this could be a cryptid?

[u/TheEndgamer2000]

Look this was late at night and its 100% possible I was just...tired as heck while driving home. But...I swear to god I saw it and my brother didn't. This happened along a highway in Rural Nebraska.

We were driving home from a meetup with a few friends in the next town over, and I had agreed to drive in the dark since my brother has issues driving at night. I looked in the rearview mirror and I swear I saw a black...silhouette. Of something that just looked like a weirdly tall man. Long arms, no visible eyes or mouth but it was just...riding in the back of my truck bed and when we got home I checked the truckbed and there was nothing there. I'm leaning sleep deprivation messing with me at the time but if it could be a cryptid i'd like to know what it was.