I think basic rhythms sometimes have names but I'm not sure where to get started finding names for easily recognizable rhythms and basslines.
What is that bassline rhythm called?
Both songs do sample from a similar source: 50 Cent's sample is from a song by the Trammps called Rubber Band, and the Christina Milian song uses Jackie Moore's Clean Up Your Own Yard. Both are R&B songs from the early 70s, which is why they share a similar groove - so, if you want to call it something, early 70s R&B should be a sufficient description. Or, reference the songs in particular.
In terms of rhythms and basslines that do have names independent of a genre, these are usually limited to the very basics, like a walking bassline, or a swung rhythm, or even a polyrhythm. As you can see, these are a part of musical theory that can be applied in just about any genre.