Yes, the original is a variant of a truss roof, a W-truss. The construction also includes the beams in the attic floor. If you had shown image 2 from the beginning, the answers would have been more precise. Removing the large sloping support leg results in significant weakening, not only of the roof but also of the floor. I suggest you restore it.
As a curiosity, I can add that I watched the neighbor's roof renovation today, a house from the early 1800s I would guess. The rafters have bent down up to 20cm in parts of the roof where the support legs were removed for more space in the attic about 80 years ago. To get it reasonably straight again, he has had to tear down the entire roof of 400 sqm down to the roof trusses and align all the rafters with 225x45 on each side. So it can become expensive in the long run to remove support legs.