Should I choose SS over bodyweight training at all?

Context: I am a ex-fencer in university, who is trying to get back into shape. In high school, at top shape, I used to stand at 70kg (at 1.75m height) - being able to do about 6 x 3 pullups and 35 x 3 pushups along with lots of very low volume / very high intensity dumbbell work as part of my training (I was not at that great shape, but had what I needed for my sport).

Two years into the university, and this summer, I have decided to start Convict Conditioning and running, about May. Last week, I weighted myself, and to my horror realised I stand at 62.5kg. I have since added another meal to my diet and increased the amount of things I eat, and now I stand at 63.5kg as of last check - but the diet of one meal of coffee and bagel per day in this fall semester has been harsh to me.

Therefore I decided that I NEED a workout program that will allow me to gain weight / muscle mass. I used to think that I was thin in high school, but this is ridiculous. I wanted to try CC workouts in strength rep range (3x5), but it seems I have lost strength in my arms - they are of same-ish size, yet they fail at providing a single pullup in form for me.

So, I have my dilemma. I can either go with SS, which seems to be the recommended way to gather strength for novices (I lack the strength to do bodyweight exercises?), and do it to gain a solid foundation - or I can go with some bodyweight routine. I actually simply do not like working with weights, but I am willing to take the inconvenience for my own sake. Still, if there is some bodyweight routine I can follow, I would be rather doing that.

So, what should I do? I do not know/understand sports training past football (soccer) and fencing, and there is simply too many options in bodyweight training to choose.

TLDR: 1.75m, lost 7.5kg over two years to drop to 62.5kg with little strength and body musculature - need to regain weight or, well, be at a rather unhealthy feeling weight.

Require some sort of strength training that will allow me to return to a regular manly level, and someone to point at the right direction.

Note: Here is what I can do in CC for 3x5.

Pullups: Horizontal pulls? (Half pulls also failed for me, cannot test Jackknife pulls)

Pushups: Full pushups.

Squats: 1/2 one legged squats

Leg Raises: Flat straight leg raises.