How do i unlock new techs and heal ocean giant

[Scar]

had to destroy a village after turning on me instantly, so how do i heal my ocean giant and what happens when he dies? can we reawaken them?

also how do i unlock next tier that are locked just says "Develop humans differently"?

[Flamestalker]

The Ocean Giant heals himself when he uses Monsoon.

You unlock new sources by completing achievements, each one (except for the challenge achievements) has a new source behind it waiting to be unlocked.