Which program or software do I need to use to replicate more of these gifs?

https://imgur.com/BeGINhV

I’m planning on making tons of GIFs / animated images, but would like to know where to start.

Answer

That is not a GIF, that is an MP4 file, but ok, that is a minor detail.

You need a program to draw the elements, a person, the screen, the shadow. Use a vector-based program.
- Inkscape => Free
- Illustrator
- Corel Draw
- Affinity design
- Gravit Design
- https://duckduckgo.com/?q=vector+based+program&atb=v147-1&ia=web
A program to animate the elements in a loop.
- Blender => Free
- NCH Animation Express => Free
- Hit Film Express => Free
- After effects
Probably a program to convert the rendered video into an animated gif.

Attribution
Source : Link , Question Author : user146368 , Answer Author : Rafael