Numbers 1:4Meaning & Commentary from the Church Fathers

Indeed, God clearly instructed Moses and Aaron, ‘There shall be with you out of every tribe one man, who is chief in his generation.’ Thus, each tribe selects a leader to act as a protector, chief adviser, and overseer of the actions of those who are stronger and more valiant; they symbolize the angels who watch over the elect and those whose names are recorded in the book of life. It is affirmed of every righteous individual that ‘The angel of the Lord shall encamp round about them that fear him, and shall deliver them’ (Psalm 33:8).

In Exodus 38:21, it was commanded that the census of the people be conducted "by the Levites, under the supervision of Ithamar the son of Aaron, the priest." Additionally, it was instructed that notable individuals from each tribe, who also served as leaders of the military, be appointed based on this census. It can be reasonably inferred that these individuals were likely the same ones appointed as leaders over the people in Exodus 18:25 by Moses himself.