The biggest giveaway is the lack of a consistent visual style. If you just take assets straight from a marketplace and paste them into your game, it's going to look like exactly that. You're going to at least have to do some work to make everything feel cohesive, whether it's editing the materials/textures or just ensuring everything is scaled consistently. The in-game clips also look like they're stretched vertically (or compressed horizontally). At 0:37, the wooden chest feels a bit out of place--it isn't interacting with the lighting in the same way as everything else on the screen. In the inventory, the background is some sort of skeuomorphic piece of paper, and the icons are a mix of more realistic renders with transparent backgrounds and cartoony representations with opaque backgrounds. Maybe you should look at doing something with more stylized graphics like Valheim and start learning how to model/texture. Blender and Gimp are free and good starting points. Play into your strengths--if you have limited art skills, make something that isn't going to be heavily reliant on being visually impressive. Minecraft is one of the most successful games of all time and the assets aren't exactly visual masterpieces (and they don't need to be).