First of all, I think it's socially responsible to mention that I'm not an expert. I'm not an expert in networking, in web development, or in cyber security. I'm a college student majoring in cyber security, and my only personal experience developing websites is developing a local host site with and without SSL for a class project, the goals of which were to show the difference in the network traffic between SSL and non SSL.
That being said, the point is that at first, you'll probably just get up a simple html page saying "hello world". There's not a whole lot an attacker could do with that, as the attack surface is very small. Think of attack surface as like a house ... if you build a house and only have one door, there's a very small attack surface. IE, only one way for an attacker to get in. But once you start adding more doors, more windows, the attack surface increases, especially if you're new to building houses, doors, and windows.
When your site gets more complex, and it inevitably will as you progress through learning, your attack surface is going to increase. As you're just learning, you're almost 100% guaranteed to not implement best security practices, so your site is going to be vulnerable.
If your site is public facing on the internet, there is probably a 100% chance that your site will get owned by a hacker. There are literally billions of people that use the internet, and there is a very non significant percentage of those users that are malicious hackers that do things like scan entire network ranges for vulnerabilities, search shodan for insecure internet facing devices, and try to exploit them when found.
If an attacker can connect to your site on your LAN, he can intercept the traffic in a proxy like burp suite, and manipulate the traffic. If he can own your site and get root access, he can pivot and try to compromise more devices on your network. You say nothing important is done on your LAN, but you're posting from a computer or mobile device on your LAN, are you not? Do you want the chances of your posting device getting owned increased? Your LAN is your LOCAL area network. It is your home, or business network. It needs to be secure. Hosting a public facing DDNS website from your LAN while you're learning web development is not how you keep your LAN secure.
The best way to learn is to do so in a safe manner, and just willy-nilly creating a web site and putting it up on the internet as you're learning, jeopardizing your LAN and all the devices on it, is not a safe way to learn. You should strongly consider using virtual machines, create a site accessible only on your LAN, not accessible at all via the external internet, and learn to develop secure websites before publishing one on the internet.
And when that time comes, linode.com has some very reasonable web hosting plans. They are very highly regarded, and when the time comes for me, I will be choosing them as a web host, fwiw.
Finally, all of that being said, when the time comes that you feel confident in your web development abilities, and you are ready to have your own internet facing web site, your network bandwidth is entirely insufficient for hosting a website, outside of receiving like maybe a few hundred visitors a month. You have absolutely zero capabilities for scalability with such a network connection. And such asymmetrical network connections (download and upload speeds are not the same, upload typically much slower) are completely standard for consumer grade internet plans. Your ISP probably even "outlaws" hosting a website with your connection in your terms of agreement. And the short of the story is just that your internet connection just cannot support a website with the potential to grow. This is one of linode's strengths - scalability. You can start small and grow. You have zero room to grow on your home network.
But all that being said, yes, DDNS (Dynamnic Domain Name Service) is what you would need if you did want to host a website from your home connection, because you almost certainly have a dynamic IP address that changes reguarly, rather than a static IP address that never changes. DDNS keeps your current external, ISP provided IP address current, so it is technically possible for users entering "yoursite.com" to have DNS resolve your domain name to your IP address. But as said, it's entirely unpractical because of your internet speeds.