Nicely done.
From the human perspective, in my opinion, the most important contribution of Obamacare was to ensure legally that no one could ever be turned down for health insurance, regardless of pre-existing conditions - and even if one had a pre-existing condition, they would not be financially penalized for it. It is hard to believe that we used to be the only developed country on the planet in which there were serious doubts, questions, and financial obstacles in being able to realistically get health insurance - under the old system Republicans preferred.
From the policy perspective, the most progressive contribution of Obamacare was the expansion of Medicaid. Which is really just a first step, hopefully, towards universal single payer health care. Even Red States are now begging for the Obamacare Medicaid expansion, as the election on November 7 demonstrated.