I don't think that he is. It doesn't make sense that one person could build an entire city, as well as his own tomb location. I believe I have mentioned my idea before, but I'll mention it again. I think it's a wonderful idea to have Jak be part of the lineage to the house of Mar. Naughty Dog could use this plot element to their advantage, to explain the channeling of eco that both Jak and his father were capable of. They could also use it to explain why Jak survived two years of nothing but Dark Eco experiments. Still, I'm curious about some connection that could be tied together in the plot. Vegar mentioned taking Jak from Damas for his Eco experiments. Could this have any connection with Baron Praxis wanting the "dark warrior?" I don't think that Jak is THE Mar, since that would bring up more questions to the story than Naughty Dog could possibly answer. It's impossible for me to imagine one person doing all that labor.