Best way to diversify/save?

Savings just needs to be your emergency fund: 6+ months worth of expenses. Once thats hit, you don’t need to keep adding to it.
Any short term goals can also go here.
Don’t bother with CDs, outdated products, its rare they can be beneficial.
Having Roth IRA is great. (its Roth, not ROTH. Its a proper name).
Do you have a 401k through work?

Once you fill up that stuff, anything more goes to a regular brokerage.

You don’t need individual stocks. Stick to index funds like VTI or VT. Less risky and more diversified. Much easier to manage 1 fund like VT, than a pile of individuals.

House fund just figure out what down payment would likely be + closing costs and save for that along with your emergency fund.
See how long it would take to build that up. You don’t want to burn through everything you have for a house. Wait till its actually doable.

Once you do have a kid, open a 529 for them.

Consider this: https://www.bogleheads.org/wiki/Three-fund_portfolio The bonds are the part that adjust volatility level (if you really can stomach 100% stock, they can even be set to 0%, however not everyone is actually able to tolerate 100% stock). More bonds should equal less volatility. Alternatively, a target date (index) fund or target allocation (index) fund are effectively the 3 fund concept in a single wrapper, managed for you. They are designed to be “one and done,” the only thing you hold. They’re fully diversified internally for you. These can be found with expense ratios as low as 0.08%-0.12% for the Fidelity, iShares, Schwab, and Vanguard index based ones. The target date and target allocation funds typically are not recommended for taxable accounts but are fine for tax advantaged. VT (2 letters)/VTWAX would cover both stock roles in one fund.

Edit: Roth IRA, not ROTH IRA. It isn’t an acronym, it was a person’s last name.