Your argument that Jeb and Marco is more conservative than .Trump depends on one’s definition of conservatism. I do not consider open borders and amnesty conservative. I do not consider free trade, as opposed to fair trade, conservative.
I consider putting America’s best interests first, having secured borders, improving the economy through smart business planning, protecting the elderly, infirm, and vets conservative.
I said that their records are more conservative than Trump's. I am not aware that either Rubio or Cruz has ever proudly boasted of being pro-life and pro-gun control, or has written checks to Hillary Clinton. On his record, Trump is at best a northeastern liberal Republican who has never taken a political position out of favor with the Manhattan celebrity circuit.
Trump now claims to have switched sides. Maybe the conversion is genuine. I hope it is. I would simply note that a lot of people are buying a pig in a poke. There should be more caution and less eagerness to nuke anyone who raises a word of caution, which is what the Trump folks are doing. Probably because they don't want to look closely at the record.
I noted before that Trump is doing especially well with two groups of people. The first are the "mad as hell" conservatives, who seem less interested this year in beating the Democrats than in blowing up the Republican establishment. (And who are carelessly defining the "establishment" as anyone who questions Trump.) The second are new, unconventional, and crossover voters. Many of these folks are distinctly more liberal than the Republican base. They apparently see Trump as a dealmaker who can work across the aisle -- and Trump is now playing up to them, with his recent assertions that he is now winning a lot of establishment support, and is in fact the new establishment.
Should Trump win, one of these two groups is in for a nasty surprise.