First, I'm just curious, how new are you to pixel art? If you don't have much experience, it's probably not the best idea to bother yourself with animating yet. It's like trying to play ice hockey before you learn how to skate.
Second, I'd like to take those examples one by one.
On the first, I don't mean to be too blunt, but it look like he's humping the air, because you just have two pixels extend from his crotch area and his head and arm going back. The second looks the same except he swings his right leg and arm forward between the cycles. And then there's that other line that I'm guessing is supposed to be his other leg once it comes back to the ground, but it never moves, even when it's supposed to be taking a step in the other frames. Which just makes those two pixels look more like his wang.
The third is better, but he barely has legs. You could make it work, but right now he's just swinging his arms and legs back and forth, because you used the same motions in reverse. Get up and take a few steps. Do your legs move the exact same way forward and back? Well, no. One reaches forward, plants on the ground, then moves back as the other reaches forward, and picks up after the other plants. Only hitting and leaving the ground once in each cycle.
I also don't really know what angle it's supposed to be. If it's from the side, keep working with the sprite from the first two examples. Give him two separate legs and arms, and have the legs move in a cycle. They should also make the exact same movements.