The problem: you can't see how tanky heroes are.
The fix: You have different colours for every 1000hp (for example).
First 1000hp could be green
If the enemy Kelvin has 1700 hp then you would have a yellow bar (for example) filled up 70% over the green health bar.
If the enemy Abrams has 3200 hp then you would have a blue bar (for example) filled up 20% over the yellow health bar.
This way by looking at the colour you'd know exactly how tanky they are + how much hp they have left.
The fix: You have different colours for every 1000hp (for example).
First 1000hp could be green
If the enemy Kelvin has 1700 hp then you would have a yellow bar (for example) filled up 70% over the green health bar.
If the enemy Abrams has 3200 hp then you would have a blue bar (for example) filled up 20% over the yellow health bar.
This way by looking at the colour you'd know exactly how tanky they are + how much hp they have left.