TikTok is an entertainment app whose users range from the young to the old (from children to seniors). Anyone can shoot a short video about anything with this multifunctional app. If someone is looking at his(their) phone which is playing some kind of song on repeat, and they have a smile on their face, he(they) might be playing a TikTok video at that time. The reason why Chinese people are so attracted to the app may be related to those things.
First, the app is designed to be easily used by everyone. Even someone who hasn’t received an education will be able to use it well in just a minute. A simple application leads to widespread usage. There is no denying the fact that digital technology brings a lot of fun to us. Tik Tok offers hundreds of video modes and facial effects for diversity of videos. People can comment and give likes to the videos they admire (give thumbs up to the videos they like), which can be considered as a means to connect different people. Despite the pandemic situation, we're still looking for fun when we're stuck at home. Since life has been been hit pretty hard with covid 19, the happiness that TikTok brings/gives us might ease the burden on mind and body for a while.
A few suggestions in brackets but you are still correct. "Seniors" are elderly people, maybe above 65 yrs and above.