I have spare cash of $5k. Where should I start with for investment if I don't mind keeping it there for 15 years?

Check out IWDA or VWRA listed on london stock exchange. These 2 ETF are diversified globally. Simple and don’t have to do anything. The ETF expense ratio is low. Investing in ETF itself is way cheaper than investing through robos. When you invest through robos, robos charge a annual management fee and on top of that the underlying ETF charge a management fee. These fee will eat into profit significantly in the long run

Can also check out Standard chartered. They don’t charge annual custodian fee at all. But if you are under 21yo, then you can’t apply for tht broker.

U can consider roboadvisors like stashaway. U can consider investing a bit every month instead of investing a lump sum of $5000 for dollar cost averagin.