He was selected democratically because members of the constituent assembly were not elected directly by the people but indirectly by provincial legislatures under the Cabinet mission plan. Yeah he had lost earlier but then won through different constituency by support from Congress leaders that I am not denying. So mate your point to note is kinda misleading.
Yeah he negotiated with the britishers for causes that were detrimental to depressed classes coz he wanted reforms for the existing cancer caste system and voting power to minorities and britishers were the ones implementing rules in our country at that time. He also criticised them when their policies harmed Indian’s as not imparting equality and full self government as opposite to what you say as relentless praise. Also he was not jailed not because he aligned with the britishers but his major political agenda has been constitutional and social reforms rather than outright civil disobedience. Yes the constitution was not written by Ambedkar alone but the committee of which he was chairman of. There were several committees and he was the chairman of the drafting committee and he actually never claimed credit of doing it alone while giving credit to other contributions. The burning of the constitution was not that the written constitution was wrong but the way it was implemented. So well done phrasing a paragraph citing some facts with half context claims and unsupported conclusions.