Server responds with status 405

I'm running into a small issue with my "server". So while I'm trying to learn backend to frontend communication, I was messing around and trying to create an "api". Anyway, whenever I try to send a POST request, the server responds with net::ERR_ABORTED 405 error and doesn't print anything on the server. I use the VSC Live Server extension & run the server on my PC (while testing), not sure if that may effect anything.

Frontend:

<!DOCTYPE html>
<html>

<head>
    <title>Testing</title>
    <link href="https://fonts.googleapis.com/css2?family=Gemunu+Libre:wght@300&display=swap" rel="stylesheet">
    <link href="https://fonts.googleapis.com/css?family=Montserrat:100,200,300,400,500,600,700,800,900" rel="stylesheet">
    <meta charset="UTF-8">
    <link rel="stylesheet" href="style.css">
    <link rel="icon" href="/img/Senko.jpg">
</head>

<body>
    <script>
        console.log("Running...")
        const data = {
            age: "15",
            name: "John Doe",
            date: "21/12/2021"
        }
        const options = {
            method: "POST",
            headers: {
                "Content-Type": "application/json"
            },
            body: JSON.stringify(data),
        }
        fetch("/api", options)
    </script>
</body>

</html>

Backend

const express = require('express');

const app = express();
app.listen(5500, () => console.log('listening at 5500'));//Doesnt work no matter what I listen to.
app.use(express.static('public'));
app.use(express.json({ limit: '1mb' }));

const allData = [];

app.post('/api', (request, response) => {
    const data = request.body;
    allData.push(data);
    response.json(allData);
    console.log(allData);
});

The error message:

POST http://127.0.0.1:5500 net::ERR_ABORTED (Method not allowed)

I appreciate any help here.