Start with community
You can't build a community without a vision. You need a simple idea to rally the troops--that's why simplicity is important at the beginning. You're obviously going to develop a lot of complexity if you have a mission bigger than you can tackle on your own, but complexity isn't a good entry point for building community.
Creating a DAO (Decentralized Autonomous Organization) is the blockchain-native way of building community. You issue a token to members (typically raising money in the process), and let DAO members vote on proposals (which sometimes include releasing a portion of the funds raised). If you need funding and want your community to have a sense of ownership, DAOs are a good way to offer that. The tradeoff is that you don't have control. Decentralized decision making might not work well with your goals, so be sure to consider the impact of this decision.
If you can align your goals with those of the community, then a DAO can be a very interesting tool for building that community. It's a great way to get feedback and directional advice from invested members even before you've built a product.
Whatever you do, don't treat the funds you raise like your own personal bank account. They (should) belong to the DAO members in proportion to their token holdings. If you (or anyone else) wants to draw down some of those funds, you'll have to exchange your tokens or make a proposal to the community.
Whether you use a DAO or not, doing big things requires more people than just yourself. You can run the show yourself, but you still need a community.
P.S. If you think a DAO sounds interesting for your vision/mission, check out my latest podcast interview with Anisha Sunkerneni on accessible DAOs.