These ones are much better.
The guy: looks pretty good. Your strokes don't look confident enough...it's clear that you drew over the lines many times...also with a pencil drawing I think it is unnecessary to attempt to do all the shading and everything by rubbing, not saying it's wrong to do that though.
Magazine girl: Wow, nice face
You got the lips right. Proportions on everything but the face are horrendous, but the face itself is very well done. Biggest problem is that the upper nose looks a bit square due to the shading...but proportions of the facial features look very good.
Baby boy: The face on this boy is even better. There's an odd little bit of shading on the left side of the nose but it's hardly noticeable. Unfortunately the image as a whole does not stand up because you put so little effort into the background and the woman's back. This doesn't really matter because it's all for practice anyhow, but it's a shame because the baby boy looks so good. (The shape of the mom's shoulder, and the skin folds / arm pit are missing...clouds and water look bad.)
Eyeball: Well, it looks fine. But eye's are also extremely easy to draw like this. The hard part about eyes is not making something that looks like an eye, but getting them to match the expressions you see in real life!
Is it worth tryign to get better? Of course...
It takes a certain small level of intelligence to be an artist...but most humans have it. Beyond that, all you need to do is practice. Learning to draw is a task just like any other and you don't need a magic gift to be good at it. Some people will have natural abilities...but if ANYONE really puts in the effort, they can become amazing.
From your drawing style, I'm going to guess that you are about 16 years old (and a boy). Based on that judgement, I would say your artistic talent so far is definitely above average, but not good enough yet. But if you put in the practice, you could become extremely good.