Rumba is generally one of the easiest rhythms to learn. The steps are few in number and fairly simple, and the music tempo is usually slow. The figures are also quite versatile. Speed it up and you get mambo, replace the final weight change with a triple step, and you get the snappy Cha-Cha. Invert the figures (side/slow first) and you get the beautiful and elegant Bolero.
As Rumba works with most 4/4 music and can be danced in limited space, it’s also very useful in social dancing situations. If you’re just learning how to dance, Rumba is a great place to start!