I am new, and I have a question about base defence

I am new to this game. (20 hours or something) I got the basics down. I got some story stuff. I am having a blast. This game is fun.

But I am watching a youtube series. Just seeing some raw gameplay and actually seeing how someone builds a base and does things. But this series is like 2 years old. There have ofcourse been patches and updates.

This person I watch made a stone wall. He mentioned enemies could jump over them. Also he mentioned enemies spawning inside the base. This has me wondering how does this work today? Can you build stone walls? Or do the only walls count when they are the wooden spiked ones?

On my series I just made it trough my first winter. I made 1 crappy line of walls. Enemies walk around it all the time. I have a few traps. Nothing serious. One side is completely open since I am not sure what to do with it. But I want to know these things before I invest a lot of time and effort in a wall that doesnt even work lol.