Well, just animating the pieces swinging back and forth is never going to look real. At the very least you need to add some actual deformation to the legs and arms as secondary motion. Even the stiffest person on the planet changes this stuff subconsciously for balance. Ideally of course you would animate some real walking, which your current animation is not at all. You may want to watch a tutorial on the anatomy and physics of a walk. Wouldn't even matter if you use one from a 3D program for reference....
You might think this is nuts but when I animate a walk cycle I get my phone, point it at the other side of the room, record a video, then move in front of the camera and do the kind of walk I want to animate. After importing the footage into AE I scale it to fit my character, Motion Stabilize the shot so I'm walking in place, then use my movements as a guide. I'll bet I've done it a couple of hundred times. I learned the technique when I took a class from Chuck Jones in the mid-'70s. If it was good enough for the Chuck and Disney animators, It's good enough for me. A lot of animators still use these techniques today. It takes years of experience to make a character walk properly without a guide or the kind of automated physics available in 3D apps or Adobe Character Animator.
What you are missing are compression and anticipation. Almost everything moves when you walk. It takes a while to get that down so. I highly recommend that you buy and read a dozen times The Illusion of Life: Disney Animation by Ollie Johnson and Frank Thomas. Understanding those principals will improve all of your animations from simple titles to the kind of thing you are trying to do here. Put in some of the Illusion of life and your animation will look much better.
I think embedding videos is broken so here's the link: https://vimeo.com/93206523