Agile is known everywhere. Most folks know the terms and activities. That is your main challenge.
What you see is not agile. but it is likely that the people involved are not ignorant about agile and terms used.
More learning is required by you.
a starting point for testers finding themselves in a new company and wanting to do Agile, but still not knowing enough about the company culture and the coworkers to start pushing for changes.
A good question though. The answer is to spend a few months learning why they aren't agile. Listening to spoken words and watching unspoken body language. True agile doesn't mean the ceremonies commonly referred to. There is no mention of a stand-up in the manifesto :) A truly empowered workforce could have different approaches to different problems.
When agile isn't present you need strong buy-in all the way up the management chain. Arguments from the bottom are hard to make and of course change is really hard for everyone. Even if you have stand-ups and ticket-grooming, it's all 'in-name only' with the intent likely lost unless there is major buy-in at the C suite and all levels of management. Changing to more agile practices is a multi-year process for many large companies that requires dedication, focus and whole company commitment. Testers don't usually get the authority to drive that message.
All said, my answer to your question is to switch from the "big picture of introducing agile into the organization" and focus on testing for agile environments This means focusing on the test pyramid, how it exists and what it promotes, focus on unit, integration and UI testing, Focus on 'quadrant 4' issues such as usability, performance and security. Focus on the benefits of TDD and BDD by using them yourselves in some way. You will likely have a more
receptive audience as it is likely these are terms folks already know and use and have practices for.
The big picture for Agile is that it requires changes in every aspect of the company, from hiring, to HR to compensation to reviews to physical environment to management techniques. When some pieces aren't done or funded or supported or introduced correctly, you end up with the mess we often see. Multiple rounds also lead to 'agile fatigue' where the mere mention of the buzzwords is either annoying or ignored.