PK issue: serial sequence needs updating

Running postgresql-12.2-x86_64-1_SBo on Slackware-14.2/x86_64.

My restructed business database has populated tables, but the primary keys
are not aware of the current maximum number since the table rows were added
external to postgres and read in using psql.

For example, I'm trying to add a new person to the people table which
currently has 484 rows. The insert into statement provides all columns but
the first, the PK (person_nbr) which is an int with an associated
people_person_nbr_seq. Passing the insert statement to psql is rejected
because there's already a person_nbr=1.

How do I inform the sequence that nextval should be 485? Or, do I drop that
sequence and restore it so it reads all existing table rows and their PKs?

If I didn't clearly explain myself, ask and I'll try again. :-)

TIA,

Rich