This is how I copied one sharepoint list's contents to another sharepoint list that had the exact same structure. There must be an easier way to copy items from one list to another but this is what I have for now.

jwsites-copy-sharepoint-list.js

await(async() => {
  const contextInfoURL = location.href.replace(/(^\w+:\/\/[^/]+(?:\/sites\/[^/]+)?).*/i, '$1/_api/contextinfo');
  const digest = (await (await fetch(contextInfoURL, {
    method: 'POST',
    headers: {
      Accept: 'application/json'
    }
  })).json()).FormDigestValue;

  const sourceListName = 'TrainingVideoLinks'; // Replace with your source list name
  const newListName = `TrainingVideoLinksOLD`; // New list name with timestamp

  const fieldNames = (await(await fetch(`${_spPageContextInfo.webAbsoluteUrl}/_api/web/lists/GetByTitle('${sourceListName}')/Fields`, {
    method: 'GET',
    headers: {
      Accept: 'application/json;odata=verbose'
    }
  })).json()).d.results.filter(f => !f.ReadOnlyField).map(f => f.InternalName);

  // Copy items from the source list to the new list
  const itemsResponse = await fetch(`${_spPageContextInfo.webAbsoluteUrl}/_api/web/lists/GetByTitle('${sourceListName}')/Items`, {
    method: 'GET',
    headers: {
      Accept: 'application/json;odata=verbose'
    }
  });
  if (!itemsResponse.ok) {
    console.error('Failed to fetch items from source list.');
    return;
  }
  const items = (await itemsResponse.json()).d.results;

  for (const item of items) {
    const newItem = {
      __metadata: { type: 'SP.ListItem' }
    };
    for (const [key, value] of Object.entries(item)) {
      // If the value is null or if it is not a field we care about or if it is
      // a field that should be deferred then skip it.
      if (!fieldNames.includes(key) || value?.__deferred) continue;
      // Get the value without any private properties (eg. __metadata, __deferred).
      const newValue = JSON.parse(JSON.stringify(value, (key, value) => {
        if (key !== '__deferred') return value;
      }))
      // If the value without __metadata is an empty object then skip it.
      if (newValue != null && typeof newValue === 'object' && !Object.keys(newValue).length) continue;
      newItem[key] = newValue;
    }
    console.log({item, newItem});
    const newItemUrl = `${_spPageContextInfo.webAbsoluteUrl}/_api/web/lists/GetByTitle('${newListName}')/Items`;
    const newItemResponse = await fetch(newItemUrl, {
      method: 'POST',
      headers: {
        Accept: "application/json;odata=verbose",
        "Content-Type": "application/json;odata=verbose",
        "X-RequestDigest": digest
      },
      body: JSON.stringify(newItem)
    });
    if (!newItemResponse.ok) {
      console.error(`Failed to copy item with ID ${item.ID}.`);
    } else {
      console.log(`Item with ID ${item.ID} copied successfully.`);
    }
  }

  console.log(`List '${newListName}' has been created with structure and data copied.`);
})();