How to make a good looking group picture from individual photos?

[PixLab]

First of all, I hope that you asked your friends to write theirs names as file/image name properly formated, something like "Patrice Lab.jpg" this can help if some one has a script to pick the Layer name ➤ to text layer just above in a loop... if no script around, it's still easier too double click on a picture name in the layer stack copy and past it using the Text Tool (or some one has a better idea to "automate" this process or make it easier/faster?)

Some other ways to do hexagons/shapes if you're not restricted in your creativity to pure hexagons going G'MIC (Filters ➤ G'MIC).

First simple and "automated"
Import the folder where you have all your photos as layer File ➤ Open as layer a window opens, select the first image, then hit Shift and while you're on the Shift key, select the last image (all files in between will be selected as well), then click Open.

Then go to Filters ➤ G'MIC a window opens, in the search box input "montage" (in my example just typing "mon" was enough to bring up most "montage" filters)



You can have some fun with other montage's filters







Also another "hard/long" way to do it with the GIMP's natives' tools

Filters ➤ Distorts ➤ Mosaic..., a window opens, to make the hexagons look at the options in the screenshot below.

   

Put that hexagon grid above all the pictures
then use the Scale Tool as below for each picture

   

then select the empty place in an hexagon with the Fuzzy Select tool, then Select ➤ Grow 2 or 3 pixels, then click in the layers stack the picture below this hexagon, then add a layer mask by "Selection"

Result

   

Advantage of this loonng method is that after if you change your mind, on the top layer (the grid) you can add shadows, change the grid color, add a pattern to the grid and so (also with the @rich2005 method you can do it)

PS: all people's photos in the example are from pexels.com using "face" as keyword (yes the cat did appear as well )