According to this chapter, a few of the Levites were porters; gatekeepers; guards. Perhaps these men were responsible for keeping intruders out of the temple. I Chronicles 26:17 & 18 describes the posts for these temple guards, indicating for us that there were 24 of them altogether who stood guard at one time.
Additionally there were some Levites who were in charge of protecting the treasury. Certainly the vault for offerings and valuables rightfully was to be guarded. And, there were certain Levites who didn't work at the temple at all... they had responsibilities out among the people throughout the nation (I Chronicles 26:29).
We all have our place of responsibility (I Corinthians 12:12 - 31). Not all assignments carry the same apparent weight, but all are important. Let us all take our opportunities seriously and do our absolute best to fulfill our function faithfully.