That is a better group of fish than show in the photos.
OK, here is a way to make some ideas.
Print out the largest picture you can of the materials you have, but make sure they are all to the same scale. Cut out all the driftwood, rocks and plants.
Then cut out or draw an outline of the tank. Draw the lines (lightly) that divide the tank into 5 sections.
Place the largest items in the sections next to the middle, and group the middle sized things around the main items. Make sure the main items and the secondary things are different enough to be distinct, like one log lying down and the other stump standing up.
Try to arrange the things this way:
You know how you set kids on a teeter-totter? The heaviest child is a bit closer to the middle, and the lighter children might be grouped on the other side, a bit farther away from the middle.
Think about your hardscape elements like that.
The largest, chunkiest, fattest or tallest log or rock will be the heaviest.
Smaller, long-thin, or more branch-like pieces will give the impression of light weight.
Here is what often works for me:
Divide the materials into
and into fat and narrow
Then alternate in placing them:
Put the largest/fattest to the right,
Then 2 of the medium that look different on the left, but pretty close to each other. Perhaps one standing up the other lying down,
Then back to the right with medium sized stuff, one or two,
Last scatter the small stuff more or less as part of the groups, but it is OK if the small stuff starts to unite the groups.
Then place the plants. Larger leafed plants like swords need room. They cannot be crowded into the back corners. They are more mid-tank plants so they can spread out. Do not center them, though.
I like plants that are closely related to the rocks or driftwood. Stems and blades like Val or Sag look especially nice growing up through the hardscape materials.