Here is a song to help you practice improvising. There are two bars of melody followed by two bars of backing only. You can improvise over this section. This happens three times through the song. Each two bar melody is based on several of the rhythms you have been learning.
There is much repetition of rhythms here. Repetition is important because it helps a listener to keep track and make sense of what you are singing. It also helps the other musicians you are playing with to follow you and complement what you are doing.
Many of the best melodies ever written are based on the elements of repetition and variation. The 16th notes in this solo are swung. Try swinging the 16th notes in other examples you have learned.