Besides recommendations that actually work like everyone else is saying, the "sound sharing" / "original sound" feature (don't know what it's officially called) is pretty unique, and it both encourages creation of new videos and leads to virality. If you want to make tiktoks and don't know what else to do, you can just do a dance that someone else started or re-act an existing tiktok with the same audio, perhaps putting your own spin or personality onto it. And from the other direction, if you see a funny or interesting tiktok, it's one button to see all videos made with the same audio. Also, it works -- everything in the UI is snappy, videos load even faster than YouTube, particularly on bad connections.