It's great to have fun drawing! I make my living as an artist, and it's fun, I think it's a great hobby too, so your work is great, if you want to have even more fun with your art, here are some tips:
One thing of many that an artist must have for success is enthusiasm and the desire to draw.
Your work tells me that you enjoy drawing lines, you have good clean technique, good attention to detail, precise and consistent structure.
It is good to practice your lines, I can see that in a drawing or two you have tried out perspective.
However, with the exception of the spider web drawing, I am not seeing a whole lot of passion in your pieces, and I am seeing a lot of reliablility on themes that are "safe" and "comfortable" for you.
I encourage you to move outside your regular principles, both in technique and in mood/theme, it is important to move forward and take yourself to the next steps.
For Technique:
Draw from life, buildings outside your window, clouds or foliage, etc.
Take a piece of art that you like and turn it upside down and copy it.
Arrange a still life on a table and practice drawing it.
Try to draw things that move, and try to draw things that don't move.
Study people and cars and animals and objects, notice their differences and how they need to be drawn in varying ways.
Read books on shading, volume, texture, line, perspective, etc.
For Emotion:
Close your eyes, and move your pen to the music you choose to play, or draw to sounds you hear from outside, or the news on TV.
Draw directly from your heart, draw sadness, happiness, confusion, anger, don't worry about erasing or perfection, just draw what is inside you.
Draw an entire page of doodles that have to do with only one thing, like a sport, or an animal, or one type of food, or one idea.
Basically, challenge yourself every day, reach outside of what you know, and teach yourself to draw new things, and new ideas, and your art will prosper.