Without ARP the IP connectivity is not possible.
It’s just because, IP address is a logical address and our devices are physical and they always need to handover the traffic to a physical device. And the physical device is identified by its physical Address which is known as MAC address at layer 2.
If we are considering the OSI reference model, then before sending data the device need to perform the encapsulation process. While performing the Encapsulation, the device will attach the required informations from upper to lower layers sequentially. For example if you are sending a ICMP data, then the encapsulation will start from layer 3 and will keep continue till Layer 1 before sending the data. In this scenario, at Data Link layer, the device need to mention the destination physical address or MAC address of the next device to whom need to handover the data.
Basically if you are communicating to a IP address, then the device will not aware about the MAC of the device to whom need to handover the data. In this case the ARP will be helpful to get to know the next device MAC address to whom handover the data for the specific IP address.
It’s just like you are sending a letter to your friend Hari who is staying in USA. And you need to know your next post office (Next device address) address where you need to handover the letter for delivery.