Lol I was thinking just the opposite! Around here wild grape vines grow thick and into huge tangles which can bring down a tree. Virginia creeper can sometimes do that, too. Poison ivy tends to be a bit more spindly, usually wilty almost sickly looking plant with maybe one main vine and a few small offshoots. Bot obviously different growth patterns in different parts of the country.
Either way, that looks like a big mess. First thing I'd do (assuming not poison ivy) would be to clear away a lot of the brush/vine so you have an escape path. If anything rolls, falls, or doesn't go exactly to plan and you are waist deep in vines and branches, you're likely trapped there and just along for the ride.
On the poison ivy, I think everyone is 'immune' (or have just never come into contact with the real stuff) until they are not. I was immune until I wasn't. Friend of mine was immune until he was clearing up a big patch - ripping it up by the armload and carrying to the brush pile to burn. (his words) After waking up in the middle of the night 'on fire and itching' and a trip to the ER, rounds of corticosteroids, a week off work and and a pretty rough go for a couple more weeks, he is no longer immune, either.