Is it okay to start this super famous game now?

This game matches players based on trophy count, so when you first start, you'll be matched with similar beginner players or AI bots. You don't need to worry about getting stomped by veteran players at all. You might be concerned about differences in items and stats, but in the early stages, you can win just by relying on pure skill and understanding the map's characteristics. Also, if you consistently complete the daily quests and claim free rewards, you can quickly level up your brawlers without spending any money. The game itself is perfect for jumping into and enjoying casually because each match lasts only about 2-3 minutes, making the barrier to entry low. Instead of aiming for high ranks initially, I recommend starting by collecting characters you like and getting a feel for them. Hesitation only delays the start, so just download it and play a casual match!