There are two main possibilities for HR to reply to you: 1. There are some highlights in your resume that make him feel that you are partially suitable for this job; 2. If you apply for the same position in the same company many times, HR may think you are persistent and practical.

Judging from your reply email, it shows that your experience should not fully meet their requirements, at least lack of experience, or you have not fully demonstrated all the abilities they want; Another possibility is what you call a polite refusal.