Paul continues to use "we" to refer to himself and his traveling companions and "you" to the Thessalonian believers.
Paul often thanks God for their acceptance of the gospel message he shared with them.
"Word of man" here is a synecdoche for "a message that comes simply from a man." AT: "(it is) not a message that is made up by a man" (See: rc://en/ta/man/translate/figs-synecdoche).
The Thessalonians believed Paul's message as coming from God, not from Paul's own authority.
"Word" is a metonym for "message." AT: "you received it as it truth is, the message that comes from God." (See: rc://en/ta/man/translate/figs-metonymy)
Paul speaks of God's gospel message as if it were a person who was doing work. (See: rc://en/ta/man/translate/figs-personification)
"Word" is a metonym for "message." AT: "It is this set of God's instructions that enables those of you who believe to work well together"(See: rc://en/ta/man/translate/figs-metonymy)