If you want to demonstrate to your team their progression, then job titles are important.
As a leader you might wish they weren't, but they are. They are an individual's tradable token that identifies them and what they do, both internally and externally. They are the public indication that someone is progressing. They indicate to someone what's expected from their jobs, and having explicit titles (and therefore hierarchy) removes (some) of the room for implicit biases.
However, we know that the same title in a 50 person start up, and a 5000 person corporate can mean a completely different level of job. So if we're looking to manage our growth from 50-5000, how can we set our business up for success with the titles we choose?
There are, generally, three approaches.
Seniority based titles where the title roughly corresponds to the industry expected level for a role. These might include titles such as Associate, Junior, Mid-Level or Senior. Intercom's Product Management ladder for example.
Numerical titles where progression is indicated purely by an increasing numerical value. For example Engineer I, Engineer II Engineer III. Rent A Runway's Engineering ladder shows this progression.
A mix of the two. For example Monzo.
What are the pros, cons and other considerations of the different approaches?
Seniority based titles
Gives internal and external clarity to a role - when done right your team members should know exactly where they're at and how it compares across their industry.
It helps the underrepresented appreciate their true role - giving someone a Senior title, provides confidence in their abilities. If someone has Junior it encourages them to be able to ask for help.
If someone gets given the wrong title they can get stuck in a role, and it becomes difficult to show them progression.
It's hard to add levels when you're growing, and you can get into problems with job title inflation. You gave someone a Senior title to show progression when you were small, but they're not at the level of the Senior people you're trying to hire.
Other considerations of this approach
Do you want your titles to be purely seniority based, or functional. For example do you want to include functional titles such as Head of, and if you do, are you happy with there being multiple 'Heads of' in due course?
Ensure industry relevance. The point of this approach is clarity, so ensure you're titling has relevance within your industry. There's little point in using this less flexible approach if you're not providing clarity with it.
There are jobs in the world that have creative job titles 'Creativity Ninja' or the like. The companies tend to be larger, and have hiring brands that allows for it. Whilst it may seem like a good way to stand out, it could also block both the internal and external visibility of what each person does.
Avoid bias in your titles. It's vital to not use biased language in your titles. Particularly if you're being creative.
Numerical based job titles
The principle advantage of numerical based job titles is its flexibility. If you need to add levels, it's no big deal, you can add them easily.
It will be understood internally, and can be used company wide
The major cons are there's no external relevancy. This is a problem for your team members if they're looking for another job (something you probably don't mind about), but is also a problem for hiring. If someone is a Principal somewhere, how are they going to feel about becoming a '5'. Or will they even see the job ad and apply?
This approach requires strong opinions. If you come up with something that works for you organisationally and isn't held by industry conventions, it'll give you extreme flexibility moving forward. For it to land take a strong opinion (our most junior level is level 4) or something to separate yourself from any comparison, put in strong internal rules around levelling, and you'll have yourself a strong title structure.
Using both approaches
Using both approaches, with numerical lower down (Engineer I, II, III), and seniority based higher up, can help by giving you flexibility at the areas you need the most growth (usually junior levels), but give your key senior hires the stamp of a title they want.
There is no perfect answer to titles, which is why so many companies do it in different ways. If in doubt aim for internal consistency and use the principle:
Titles should do no harm
Anything you can manage beyond that is a bonus.