use \Magento\Framework\App\Bootstrap;
include('../app/bootstrap.php');
$bootstrap = Bootstrap::create(BP, $_SERVER);
$objectManager = $bootstrap->getObjectManager();
$url = \Magento\Framework\App\ObjectManager::getInstance();
$storeManager = $url->get('\Magento\Store\Model\StoreManagerInterface');
$mediaurl= $storeManager->getStore()->getBaseUrl(\Magento\Framework\UrlInterface::URL_TYPE_MEDIA);
$state = $objectManager->get('\Magento\Framework\App\State');
$state->setAreaCode('frontend');
/// Get Website ID
$websiteId = $storeManager->getWebsite()->getWebsiteId();
echo 'websiteId:'.$websiteId." ";
/// Get Store ID
$store = $storeManager->getStore();
$storeId = $store->getStoreId();
echo 'storeId:'.$storeId." ";
/// Get Root Category ID
$rootNodeId = $store->getRootCategoryId();
echo 'rootNodeId:'.$rootNodeId." ";
/// Get Root Category
$rootCat = $objectManager->get('Magento\Catalog\Model\Category');
$cat_info = $rootCat->load($rootNodeId);
$categorys=array('Levis','Wranglers','Basics'); // Category Names
foreach($categorys as $cat)
{$name=ucfirst($cat);
$url=strtolower($cat);
$cleanurl = trim(preg_replace('/ +/', '', preg_replace('/[^A-Za-z0-9]/','', urldecode(html_entity_decode(strip_tags($url))))));
$categoryFactory=$objectManager->get('\Magento\Catalog\Model\CategoryFactory');
/// Add a new sub category under root category
$categoryTmp = $categoryFactory->create();
$categoryTmp->setName($name);
$categoryTmp->setIsActive(true);
$categoryTmp->setUrlKey($cleanurl);
$categoryTmp->setData('description', 'description');
$categoryTmp->setParentId($rootCat->getId());
$mediaAttribute = array ('image', 'small_image', 'thumbnail');
$categoryTmp->setImage('/m2.png', $mediaAttribute, true, false);// Path pub/meida/catalog/category/m2.png
$categoryTmp->setStoreId($storeId);
$categoryTmp->setPath($rootCat->getPath());
$categoryTmp->save();