Should every language I have seen go on the resume?

No. List languages you can work in without relearning them from the start, and make sure each one appears in a bullet. A language you only sat beside is an interview comment, not a skill.

How specific should a bullet be?

Specific enough that a teammate would recognize the work. Name the system and your action. Skip figures you would not walk through out loud.

Software engineer resume tips

A software engineer resume is a record of software that had to work for someone else. Reviewers skim for the kind of system, the part you owned, and whether a teammate or a customer of that product could tell you had been there. A long list of languages does not answer that.

Cover letter for a software engineer

What to put first

Put the title you are aiming for in the heading, then one line on the environment you know: a web service, a mobile app, a data pipeline, embedded software, or internal tools. The first bullets should be work you did, each naming the language or platform you actually used.

Show the part you owned

Write what you built, fixed, or kept running, and who depended on it. "Worked on the API" hides whether you designed it, reviewed it, or deployed someone else's change. If you were one person on a team, say what your part was.

Put tools after the story

A skills line helps when it matches the bullets. If a posting names a database or a framework, use that word only where you used it. Do not copy the posting's stack into a skills section to look closer to the job.

Keep it readable as text

Hiring software often reads the file as text, not as a designed layout. Keep the target title in the document, not only inside an image. Put dates and employer names in the body so they are not trapped in a header graphic.

An example line

Adapt this only where it is true for you. It is a shape for a bullet, not a claim that a particular person did this work.

Owned the checkout API for a retail service: moved tax calculation into its own step so a pricing change no longer required a full deploy, and named the language that step was written in.

What to leave off

Leave off tutorials you finished but never used in a job or a substantial project, languages you cannot write in today, and results you could not explain if someone asked how they were measured. A shorter resume you can defend beats a full page of tools.

Questions

Should every language I have seen go on the resume?: No. List languages you can work in without relearning them from the start, and make sure each one appears in a bullet. A language you only sat beside is an interview comment, not a skill.
How specific should a bullet be?: Specific enough that a teammate would recognize the work. Name the system and your action. Skip figures you would not walk through out loud.