App Inventor offers many different opportunities for sharing your app: You can download it to your own device, share it with others, or upload it to Google Play.
If you have done the latter, you are no longer seeking to be an Android developer—you are one. Even if your app is relatively simple, it marks an important milestone in the process to building apps for the Android platform.
The journey through MIT App Inventor should have taught you valuable skills for computational thinking and application design. With this skill set in place, you can take this knowledge as far as you wish and build apps of deeper sophistication and complexity.