Actually quite well done. The good stuff:
1. Good melody. Catchy, natural, sensible.
2. Good structure. Sensible developmental arc, sensible recap.
Now some suggestions:
1. When repeating stuff, consider introducing tiny little variations here and there instead of repeating literally. (Example 1: mm. 14-17 is a repeat of mm. 10-13; a "tiny change" may be as simple as changing the second "g" in m.16 to a "a-flat." Example 2: mm. 23-24 is a repeat of mm. 21-22; a "tiny change" may be as simple as changing the melody's "a-flat" in m.24 to a "b-flat" and reharmonize m.24 accordingly with a V chord.)
2. Let it "breath" from time to time ... ever since the end of the intro (m.9), the music just keeps chugging along relentlessly; there is always some notes playing in every beat from m.10 all the way to the end. Yet in there you have switched motives many times. See if you can find places for the music (not just the melody, but also the accompaniment) to "take a break" from the constant movement. (These opportunities typically occur when you change motives; e.g., m.40
It's usually a very good thing to have and keep a groove going, but since you're not really arranging for a night club dance track, it wouldn't hurt to let the music "pause" every once in a while to enhance the drama.
3. Rhythmic or style change in the accompaniment ... can consider occasionally changing the rhythm or style of the accompaniment, especially when you change the motive in the melody. The ears fatigue if they keep listening to the same sort of thing over and over after a while, so occasionally changing things up helps keeps the music appear "fresh" to the typical human ear.
About the harmony ... yeah, pretty standard chord progression, but as a piece of pop/easy-listening music, that's actually par for the course. Many pop/rock/blues artists have no problem entertaining millions with songs using only
simple chord progressions repeated over and over and over and over again. You can sprinkle in more imaginative/unusual chord progressions (and it would be a good composition exercise), but it ultimately hinges on what you really want that piece of music to be (who it is for, what it is for/about).
Very good job over all, I hope you enjoyed your composition experience so far!