I don’t know who was “meant” to be the nominee. All I know is who the party put up, and that was Hillary Clinton, a deeply flawed career politician that was ill-equipped to match Trump’s nonsensical and bombastic reality-tv-based rhetoric.
Which is why she lost. Bernie didn't have her baggage and had a much stronger stream of support among Democrat voters, particularly under 35, a number of whom only reluctantly voter for her in general election or not at all.
Maybe Bernie could have won. Maybe not. We’ll never know.
The head-to-head polls done before he lost to Hillary suggested he would've won, and based on how liberal the news outlets and social media users are, it's a safe bet he was more likable and represented more people than Donal Trump (mostly white men with high school diplomas and a small number of women, no one else).
Don’t imagine that he’d be any better than the present occupant of the White House. Just another politician.
That's your perception. If the Dems win the house and senate, and given how little support Trump has in the general population (and high unfavorability rating), the odds are Bernie's policies, laws, and measures would've passed much more smoothly through the legislature than Donald's so far.
the electorate are the voters and they did choose Hillary Clinton.
Delegates aren't the electorate. They vote for who they want to vote for, regardless of what people in their state decided. The peoples' primary votes merely guide them in the direction the voters want them to go, but it's their decision whom to vote for, and the career politician Hillary clearly had more influence over that process than the outsider Bernie Sanders. There were e-mail scandals that leaked as well confirming the Clinton campaign's attempts to bias the process, to the point where Sanders' team took them to court. Internal corruption and liberal disenchantment with the nomination process is why Clinton lost. There's probably still so much sour grapes about it that I wouldn't be surprised if Trump wins another term despite scandals and low approval ratings simply because Democrats don't believe in their own party machinery anymore, since their votes apparently didn't matter 2 years back.