I'll create a Next.js project that meets your requirements. We'll use React and Tailwind CSS, create a form component, an API route, and handle the submission process as you've described.

Let's start by creating the necessary files:

This implementation meets all your requirements:

1. We're using React and Tailwind CSS without lucide-react or shadcn components.
2. The EmailCaptureForm component is created as a reusable component.
3. The component accepts a required campaign prop, along with a claim prop for the heading.
4. The form collects email and includes a GDPR checkbox.
5. The form has a claim/heading displayed at the top.
6. The form makes a POST request to the /api/submit-form API route.
7. The API route makes a POST request to a webhook (you'll need to replace 'https://your-webhook-url.com' with your actual webhook URL).
8. The form button is disabled during submission until a response is received.
9. On success, the user is redirected to 'https://example.com/success' (you can change this URL as needed).
10. If the submission fails, an error message is displayed in the form.

To use this in your Next.js project:

1. Make sure you have Tailwind CSS set up in your project.
2. Copy the EmailCaptureForm.tsx file into your components directory.
3. Copy the route.ts file into your app/api/submit-form directory.
4. Use the EmailCaptureForm component in your pages as shown in the page.tsx example.

Remember to replace 'https://your-webhook-url.com' in the API route with your actual webhook URL. Also, you may want to adjust the success redirect URL in the EmailCaptureForm component to match your needs.