magento-module/Model/Setting/Attribute.php

<?php

namespace Retailcrm\Retailcrm\Model\Setting;

class Attribute implements \Magento\Framework\Option\ArrayInterface
{
    protected $_entityType;
    protected $_store;

    public function __construct(
        \Magento\Store\Model\Store $store,
        \Magento\Eav\Model\Entity\Type $entityType
    ) {
        $this->_store = $store;
        $this->_entityType = $entityType;
    }

    public function toOptionArray()
    {
        $types = ['text', 'multiselect', 'decimal'];
        $attributes = $this->_entityType->loadByCode('catalog_product')->getAttributeCollection();
        $attributes->addFieldToFilter('frontend_input', $types);

        $result = [];

        foreach ($attributes as $attr) {
            if ($attr->getFrontendLabel()) {
                $result[] = array('value' => $attr->getAttributeId(), 'label' => $attr->getFrontendLabel(), 'title' => $attr->getAttributeCode());
            }
        }

        return $result;
    }
}