There are more and less than you think.
Some that you consider to be a ”true“ asanas are only variations of others. A great example of variations is warrior pose, or pigeon pose.
The answer is there are quite a few numbers and sources. Some say that there are 8.400.000 asanas and variations, one asana for every human being on this planet.
The magical number is 84 of classic asanas taught by Lord Shiva and the very first 4 are most important for yogic practice.
Now what do you think these 4 asanas could be?
Maybe Tatasana, Downward facing dog, plank pose or Shavasana? No! All wrong. The 4 most important asanas are all sitting poses: Siddhasana, Padmasana, Sukhasana, and Svatiskasana.