Transferring multiple files from one folder to another using Terminal
This is more difficult than it may seem. The following assumes that all images to be copied are in the same directory (no sub directories).

cd "PATH/TO/Paras_all"
count=0
find . -maxdepth 1 -iname '*.png' -print | while IFS= read line; do
    if [[ $count -lt 5000 ]]; then
        echo cp "$line" ~/"Documents/TARGET1"
    elif [[ $count -lt 10000 ]]; then
        echo cp "$line" ~/"Documents/TARGET2"
    else
        echo cp "$line" ~/"Documents/TARGET3"
    fi
    ((count++))
done


Replace -name '*.JPG' to mach your images and TARGET1 etc by the actual names. If you run the code like that it will just print the commands. Remove the echo if the commands seem to be correct.

PS: It's probably easiest to put everything in a file with #!/bin/bash in the first line, make the file executable with chmod +x NAMEOFFILE and then run ./NAMEOFFILE.