First of all, we need to understand that cats are independent animals and they don't usually develop an intimate relationship with people like dogs. However, when your cat actively climbs on top of you, it may be because it develops trust and dependence on you.
Secondly, cats are territorial animals, and they will mark their territory in various ways, including rubbing your legs, jumping on your body, etc. If the cat actively climbs on top of you, it may be that it is marking you with its own scent, indicating that you are its "human".
In addition to this, cats also have an instinct to look for warmth and comfort when they feel cold or uncomfortable. If your cat is actively crawling on top of you, it may be because it feels comfortable with your body temperature or it is seeking comfort.
In conclusion, when your cat actively climbs on you, it may be because it has developed trust and dependence on you, is marking its territory or is looking for a warm and comfortable place. Of course, these are just some possible explanations, and every cat has a different personality and behavior. If you have any questions or confusion about your cat's behavior, the best course of action is to consult with a professional pet behavior specialist.