The boat appears to have its sails furled, with only the lines from the mast to the bow, deck and stern showing. That would indicate that the 'artist' painted what he/she saw, a boat that was hauled up on shore landing, either for repairs or to take on food and water.
The sailors may have met the artist and their 'tribe' for trading purposes or may have been hostile enemies looking for slaves, we'll never know. The animals around the boat may indicate that they were looking for animals for food or trade to take back home.
Or it may have been another Noah's Ark story.................
Decided to look into this more. Here is a Wiki article on the reed boats of Egypt and Lake Titicaca, Bolivia:
https://en.wikipedia.org/wiki/Reed_boat
In addition, here are a lot of images of reed boats. A number also have lines as shown in the rock carving. You say bow and stern, I say front and back ends, what is the argument???