One person contracting, with no employees or significant assets at risk, doesn’t gain much from an LLC or S corp. The income passes through to you as business income on your taxes regardless, so the less paperwork, bureaucracy, and fees the better.
You can easily find lots of companies selling questionable or outright useless services to new small business owners. Ignore all of that, you probably don’t need it. Do good work, don’t accept jobs from shady or pushy clients, keep records (a spreadsheet works fine). You want to optimize for billable hours, not for looking like a “real” business.
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The IRS got wise to tricks people used to restructure income with LLCs and S corps a long time ago. Complex business and tax structures for a solo or small business will just attract attention from tax authorities.
Every situation is different, especially with employees or valuable/depreciable inventory. Consult a professional if those apply, they usually don’t for solo freelancers. Sometimes you run into clients who think they can only pay to a corporation, they usually mean they want an EIN, which you can get for free online from IRS. Sometimes clients want E&O or liability insurance, I have either talked them out of that or passed on them — not worth the expense.