That's a solid start.
Some options for you:
-Planks to get started on ab work. I started at 2x30 second planks and after about 6 months I was up to 2x60 second planks.
-Side planks. Videos of this are easy to find.
-Glute bridges. (Lay on your back. Place the heel of one foot on a raised surface like a bench, bend the knee and use that leg for balance. Take the other leg and point it straight out and up. Then try to raise your hips directly to the ceiling, focusing on your glute and hamstrings while you do it. BEWARE OF HAMSTRING CRAMPING.) People do very, very little glute work and the more I work out the more I realize it's one of the most important muscle groups for both feeling good (not having back pain) and performance (Glutes are a secret spot of weakness in many, many compound exercises.)
-Leg raises. These are tough. Murderous even. But it will work your core better than many other movements.
-Windshield Wipers. Will really work your obliques (that muscles you couldn't remember the name of.)
-Get an Ab Mat. Or use a pillow underneath your lower back. This will really put the stretch on your abs as you do your situps and they will ache like nothing else the next day. (I prefer full sit ups to crunches, what people say about your back be damned. That is almost always an issue of form, technique and weakness, not the actual exercise jeopardizing your back.)
-Russian Twists. Can be done without weights but I find adding a 15pnd dumbbell to the exercise really taxes me.
-
Chris Heria demonstrates some of these movements and a few others here.-Stomach vacuum.
Couresty of Athlean-X. While some may consider this an exercise for "stage models", we rarely think about contracting our abs using the diaphram and a lot of the other "non-show" ab muscles like the transverse abdominis. But the exercises is dirt simple to perform. I use it as a finishing exercise after my workout when my abs are already good and tired. I do 3x15 seconds, which is what Arnold Schwarzenegger recommends to get started.
-Standing bicep curls using a door frame or post. Biceps are pretty hard to work in calisthenics but not impossible.
-Hand stand shoulder press. These are pretty tough starting out and you'll absolutely want a wall to balance against. Depending on your shoulder strength and stability this may or may not be doable starting out.
-Side lunges.
https://www.youtube.com/watch?v=FUX6Pz8vV0s. They're not just for women, it works the outside of your glutes and helps you with your flexibility and core stability if done for a long enough time. What is key is to balance on one leg as you bring the other up, that really increases the demands of the exercise on your body and particularly your core muscles to stabilize you.
Also don't underestimate "plusing" your exercises. For example you can do a
push up plus to work your serratus anterior (those little rippling muscles under your pec along your side.) There are so many "pluses" you can add to various exercises to get more work out of them.
The nice part about a lot of these exercises is you can add a dumbbell for added resistance too. I do a 15 pound dumbbell held against my chest during full sits up, for example, because after a year of planks and situps with the ab mat I was finding none of these exercises were giving me the challenge (or delayed onset muscle soreness) I desired.
A couple other good calisthenics youtube channels for you.
Fitness FAQs. This guy does 99% calisthenics, peddles no bullshit at you, keeps his videos short and on point and isn't annoying to listen to. I would put him at the top.
Training Pal. I haven't watched as much of his stuff as when I started but it's still a no nonsense calisthenics focused channel with good information.
Chris Heria as mentioned. Also a channel that is about 90% focused on calisthenics. While you can't argue with his physique, he's pretty advanced and is in the game to make money. So you have to deal with him often promoting their training gear, programs and shit while you're just looking for some training examples. But in the scope of things he keeps it to about a medium. And he often makes incredibly difficult movements look easy due to his experience in training.....but takes the time to show you the lower level progressions and where to start.
Tapp Brothers. These twins are more focused on Parkour than anything else, but all their exercises qualify as calisthenics. I find their delivery a little on the amateur side but they've got some good tips as well.
And always try to keep your rest breaks between sets to a minute or less to maximize both fat loss (by keeping your heart rate elevated in the fat burning zone for longer, consistent periods of time) and muscle hypertrophy (shorter rest periods = less time for your muscles to recover = maximum muscle fiber recruitment because they're working while already tired.)